Birdsong is a highly stereotyped behavior that is learned by adjustment of vocal output to a memorized song template by way of auditory feedback. Because song learning involves the interaction of vocal motor output and auditory feedback, a characterization of the relationship between these two events is critical for understanding the neural bases of vocal learning. The present proposal investigates the relationship between vocalization and auditory perception of that vocalization during song development. The importance of studying the awake, behaving bird, is best exemplified by the fact that auditory responses are significantly altered during vocalization. Specifically, neurons in nucleus HVC which normally exhibit vigorous responses to playback of the bird's own song under anesthesia, and during non-singing periods, become completely inhibited during and following singing (McCasland and Konishi, 1981). This vocalization-induced inhibition of auditory feedback is of great importance because nucleus HVc is thought to be the gateway for auditory information into the rest of the song control system. This proposal will characterize auditory feedback in forebrain structures of the song system and provide a detailed description of the regulation of auditory feedback during song learning. The methods used in this study will involve chronic recording from small clusters of neurons in awake, freely moving zebra finches. Because human beings and birds are the only animals known to imitate complex vocal signals and because early deafness has profound effects on vocal development in both organisms, understanding the general principles of how auditory feedback is used to adjust vocal output will provide a framework toward which neural mechanisms underlying vocal development in humans can be studied.